Combined mortise and tenon joint feature

ABSTRACT

A one piece stowage bin ( 10 ) has a generally rectangular, polygonal open-fronted box-type structure. Right and left end panels ( 14 ) and ( 18 ) rise up from the sides of the bottom panel ( 12 ) to form side walls. Three fold lines allow the stowage bin ( 10 ) to comprise the rear lower panel ( 22 ), the rear upper panel ( 26 ) and the top panel ( 30 ) of the stowage bin. Tenons ( 51 ), ( 52 ), ( 53 ), ( 54 ), ( 57 ), ( 58 ), ( 59 ), and ( 60 ) extend from the margins of the right and left end panels ( 14 ) and ( 18 ). Mortise pockets ( 63 ), ( 64 ), ( 65 ), ( 66 ), ( 71 ), ( 72 ), ( 73 ), and ( 74 ) are formed in the side margins of the rear upper panel  26  and the top panel ( 30 ). The mortises and tenons create interlocking mortise and tenon joints that do not require a bonding adhesive. Right and left formed angle brackets ( 38 ) and ( 40 ) secure the right and left end panels ( 14 ) and ( 18 ) to the top panel ( 30 ). Rear upper panel edge margins ( 27 ) and ( 28 ) and the top panel edge margins ( 30 ) and ( 32 ) contain outwardly extended bulges in the region of the mortise pockets that define minimum edge margins around each mortise pocket. Right extending minimum edge margin bulges ( 81 ), ( 82 ), ( 83 ), and ( 84 ) are staggered relative to left extending minimum edge margin bulges ( 89 ), ( 90 ), ( 91 ), and ( 92 ). Protrusions ( 120 ) extend into the interior of the mortise pockets from the sidewalls thereof to extend into the interior of the mortise pockets. The protrusions are sized to form an interference fit with the tenon tabs through a combination of spring deflection of the protrusions by the tenon tabs and local material removal from the tips of the protrusions as the tenons are inserted.

CROSS-REFERENCE TO RELATED APPLICATION

This application is a division of application Ser. No. 08/974,948, filedNov. 20, 1997, now U.S. Pat. No. 6,194,477.

FIELD OF THE INVENTION

This invention relates to the field of building construction usingmortise and tenon joints to connect structural members, such as inaerospace commodities, and more particularly, to the use of minimum edgemargin mortise and tenon joints which implement self toolingcharacteristics to produce overhead stowage bins for aircraft from asingle folded composite sandwich panel.

BACKGROUND OF THE INVENTION

The practice of the aerospace industry has been to adapt longestablished carpentry methods of joinery into aerospace commodities inan attempt to capture the advantages of reduced weight and assemblycomplexity. Substantial difficulties have sometimes been encounteredhowever, because tolerances achievable with fine carpentry inwood-working are far superior than that which can be achieved using manyaerospace materials, such as composite honeycomb sandwich panel typestructures, and their related assembly methods. Thus, time provenjoinery techniques that have been effectively implemented inwood-working applications, have proved ineffectual in the aerospaceindustry.

One such problem area for aerospace applications, which has beenencountered in the prior art, has been how to maximize the volume of adefined envelope using extended tab and pocket cutout joinery methods,while also maintaining maximum joint strength. The rabbet joint hasbecome the standard design for the majority of aerospace commoditiesthat utilize extended tab and pocket cutout joinery. In a rabbet joint,the pocket cutouts are at the very edge of the panel, with the pocketsidewalls actually incorporated into the outer edge of the panel. Thistype of joint permits joint location to occur at the edge of a panel,thus providing the benefit of a non-interfering edge profile Thedisadvantage of the rabbet joint, is that the joint must be adhesivebonded to secure the panel connection, and the primary load path isthrough the relatively weak adhesive bondline at the rabbet joint.

The standard alternate to the rabbet joint is commonly referred to as amortise and tenon joint Although, the term mortise and tenon has becomesomewhat generic in fine carpentry uses, aerospace usage has defined amortise and tenon joint as a term of art, describing a joint utilizingsandwich panel construction with square cut tabs (tenons) and blind(joint not visible after joining has occurred) slotted pocket cutouts(mortises), without dovetailing.

The bonding process of a mortise and tenon joint also involves applyingadhesive into the mortise pocket, however, since the pocket is fullyenclosed in the mortise panel (not incorporated into the panel edge asin the rabbet joint), the primary load path is through the mortise panelitself and not the adhesive bondline. The disadvantage of the mortiseand tenon joint is the existence of an edge margin of the mortise panelthat extends from the mortise pocket to the actual edge of the panel.This interfering edge margin reduces the volume which can be achievedinside a defined envelope It is desirable to have a joint that wouldprovide the combined benefits of both a rabbet joint and a mortise andtenon joint.

Another unresolved problem in the prior art is that although tighttolerance control of the standard square cut mortise (panel hole) can beachieved through the use of NC panel and profile routers, largeclearances are still usually required between the tenon tabs and mortisecutout sidewalls, in order to allow for variation in tenon panelthickness. The current state of the art in composite honeycomb sandwichpanel production utilizes a multi-opening press (MOP) process, that doesnot presently afford a high degree of control of panel thicknessvariation.

Thus, relatively large clearances must be designed into mortise andtenon joint interfaces so that costly interference conditions do notoccur, preventing the tenon tabs from fitting into the mortise pockets,and resulting in the scrapping of parts or expensive rework. These largeclearances between the mortise pocket sidewalls and the tenon tabsurfaces, increase the need for elaborate and expensive tooling toaccurately locate and secure the panels. While the panels are held inplace, an adhesive, which is used to bond the joint, is allowed thenecessary time to cure. A joint structure with inherent self-toolingfeatures that could eliminate the need for expensive additional toolingis highly desirable.

Still an additional unresolved problem in the prior art involves theefficient production of lightweight overhead stowage bins for aircraftCurrently, overhead stowage bins for aircraft are produced by joiningtogether four (typically) composite sandwich panels using structuraladhesives and either aluminum brackets fastened to potted inserts ormodified box joints (typically rabbet joints). Both of these methodsdepend on the strength of the adhesives to carry the required structuralloads.

This reliance on adhesives presents two major disadvantages. First, theloads that adhesives are typically capable of carrying are inferior tothe loads that can be carried through the composite panels themselves.Second, adhesives present substantial manufacturing problems, in thatparts must be jigged in the proper configuration while the adhesivecures, a time period generally of around eight hours. It is desirable tohave a aircraft stowage bin that can be produced without structuraladhesives.

SUMMARY OF THE INVENTION

The present invention discloses a one-piece aircraft stowage binconstructed from a single piece of folded,thermoplastic-composite-skinned, honeycomb-cored sandwich panel. Theaircraft stowage bin is formed by folding the composite material into alocking open box type structure The composite sandwich panel containsinterlocking joints which can be characterized as minimum edge marginmortise and tenon joints (described below).

A minimum edge-margin mortise and tenon joint corner structure is formedfrom a tenon panel, having tenon tabs, engaging mortise pockets formedin an angularly disposed tenon panel In the minimum edge margin joint,the mortise pockets are located along the edge of the mortise panel, asin a rabbet joint, but with the mortise panel edge containing outwardlyextended bulges in the regions of the mortise pockets, such that aminimum edge margin is maintained around each mortise pocket (instead ofthe pockets being incorporated into the panel edge as in a rabbetjoint).

In a preferred embodiment of the present invention, the single piecethermoplastic composite honeycomb sheet is cut so that sections of thesheet can be folded, using a thermoplastic folding method, to form thestowage bin. Side portions of the sheet are designed such that theirshape facilitates being folded upwards to form end panels of the stowagebin. Another portion of the sheet is designed such that its shapefacilitates being folded upwards and then over, to form the top panel ofthe stowage bin.

The minimum edge margin mortise and tenon joints are used at theconnection between the top edge of the end panels and the top panel ofthe stowage bin. The mortise pockets in the mortise portion of the paneljoint, are located along the edge of the top panel of the stowage bin.The tenon tabs in the tenon portion of the panel joint are located alongthe top edge of the end panels. This allows the minimum edge marginmortise and tenon joints to engage during the folding process of thestowage bin panel.

Finally, two formed angle brackets are through-bolted to the top panelof the stowage bin and the end panels. This provides a load path fordownloading forces and securely locks the bin together. This lockingmethod, which utilizes the formed angle brackets, allows the foldedcomposite panel to form joints that connect such that no adhesive isrequired, either to carry loading forces or to hold the bin together.The only direction in which the minimum edge margin mortise and tenonjoint is subject to detachment during loaded conditions, is secured bythe formed angle brackets.

Another aspect of the invention discloses a self aligning mortise andtenon joint structure that is formed from angularly arranged tenon andmortise panels, having tenon tabs and mortise pockets, respectively. Inmortise and tenon joints constructed of composite honeycomb material,the mortise pockets in the mortise panel must be cut sufficiently largerthan the optimal size of the extended tenon tab of the tenon panel,because of the inherent thickness variations in tenon panel production.Otherwise tenon panel thickness variation can cause an interference withthe mortise pocket sidewalls, preventing the tenon tab from fitting inthe mortise pocket.

In the self aligning mortise and tenon joints of the present invention,the mortise pocket sidewalls incorporate protrusions extending into themortise pocket, the protrusions being distributed along the sidewalls ofthe mortise pocket. During the assembly process, the tenon tabs willdeflect these unsupported protrusions slightly and/or remove materialfrom the tips of the protrusions at the points of contact, forming aninterference fit. The protrusions thus act as aself-locating/self-tooling features both to locate the tenon in thecenter of the mortise, and so that if it is desired that bondingadhesive be used in the joint, the tenon panel is secured to the mortisepanel until curing completion, without the assistance of additionaltooling devices.

A stowage bin constructed in accordance with the present invention maythus be formed from only a single piece of foldedthermoplastic-composite-skinned sandwich sheet and two formed anglebrackets. The lack of requirement for bonding adhesive greatly reducesmanufacture time, since the adhesive application and adhesive curingstages are eliminated from the assembly process. Weight savings are alsoacquired from the reduction in part count (both in brackets and panels).Further, the incorporation of the minimum edge margin mortise and tenonjoints gives the combined benefits of the non-interference edge profileof a rabbet joint, with the superior strength of a traditional mortiseand tenon joint. Additionally, this invention incorporates self-toolingfeatures into the mortise pocket cutouts, that accommodate tenon panelthickness variations by a combination of local material removal and“spring” deflection of the unsupported protrusions to locate andmaintain the tenon panel in the center of the mortise pocket cutout.

BRIEF DESCRIPTION OF THE DRAWINGS

The foregoing aspects and many of the attendant advantages of thisinvention will become more readily appreciated as the same becomesbetter understood by reference to the following detailed description,when taken in conjunction with the accompanying drawings, wherein.

FIG. 1 illustrates a perspective view of a preferred embodiment of thepresent invention;

FIG. 2 illustrates a top view of the preferred embodiment of FIG. 1showing the panel in a flat, pre-folded state;

FIG. 3 illustrates a side view of the preferred embodiment of FIG. 1showing the stowage bin fully folded;

FIG. 4 illustrates an enlarged, fragmentary, exploded perspective viewof the preferred embodiment of FIG. 2 showing a minimum edge marginmortise and tenon joint;

FIG. 5 illustrates an enlarged, fragmentary perspective view of thepreferred embodiment of FIG. 2 showing a minimum edge margin mortisepanel;

FIG. 6 illustrates an enlarged perspective view of two units of thepreferred embodiment of FIG. 1, demonstrating the staggered interlockingeffect of the minimum edge margin mortise pocket.

FIG. 7 illustrates an enlarged fragmentary top view of the preferredembodiment as shown in FIG. 2 showing a minimum edge margin mortise andtenon joint with self-aligning wave-shaped protrusions creating aninterference fit with an inserted tenon tab (shown in phantom), and

FIGS. 8 and 9 are enlarged, fragmentary top views of other preferredembodiments of the present invention illustrating shapes of the mortiseprotrusions.

DETAILED DESCRIPTION OF THE PREFERRED EMBODIMENT

FIG. 1 illustrates a preferred embodiment of a one-piece aircraftstowage bin 10 constructed in accordance with the present invention andutilizing a folded composite sandwich panel and interlocking, joints.The one piece stowage bin 10 has a bottom panel 12 which forms thebottom of the open box-type structure. Forming the side walls of thestowage bin 10 are right and left end panels 14 and 18 which rise upfrom the sides of the bottom panel 12. The remaining portion of thestowage bin 10 contains three fold lines which allow it to comprise therear lower panel 22, the rear upper panel 26 and the top panel 30 of thestowage bin. It should be readily apparent that a greater or lessernumber of rear panels could be utilized without departing from thegeneral concept of the structure described herein.

FIG. 2 shows tenons 51, 52, 53, 54, 57, 58, 59, and 60, which extendfrom the margins of the right and left end panels 14 and 18. Mortises63, 64, 65, 66, 71, 72, 73, and 74 respectively are formed in the sidemargins of the rear upper panel 26 and the top panel 30. Together, themortises 63, 64, 65, 66, 71, 72, 73, and 74, and tenons 51, 52, 53, 54,57, 58, 59, and 00, create interlocking joints. As shown in FIG. 1,right and left formed angle brackets 38 and 40 secure the right and leftend panels 14 and 18 to the top panel 30.

Describing the present invention more specifically, the overhead stowagebin 10 is constructed from a single sheet ofthermoplastic-composite-skinned, honeycomb-cored sandwich. The compositesandwich sheet is originally flat, as shown in FIG. 2. The sheet is thenfolded using a thermofolding process into its final shape as shown inFIG. 1. A preferred thermofolding technique is described in patentapplication Ser. No. 08/712,987, filed Sep. 13, 1996, which issued asU.S. Pat. No. 6,036,802 on Mar. 14, 2000.

Referring to FIG. 2, the intended fold lines for the formation of thebin's final shape are illustrated. Between the right edge panel 14 andthe bottom panel 12 is the right/bottom panel fold line 16.Correspondingly, between the left end panel 18 and the bottom panel 12is the left/bottom panel fold line 20. Continuing, between the rearlower panel 22 and the bottom panel 12 can be seen the rear/lower/bottompanel fold line 24. Next in line, between the rear upper panel 26 andthe rear lower panel 22 can be seen the upper/lower panel fold line 29.Finally, between the top panel 30 and the rear upper panel 26 can beseen the top/upper panel fold line 33. In an alternate embodiment, theright and left end panel upper edges 15 and 19, could actually befoldlines where the light and left end panels 14 and 18 attached to thetop panel 30.

The preferred embodiment as shown in FIG. 2, also discloses a right rearlower/end panel intersection notch 34 and a left rear lower/end panelintersection notch 36. These notches in the rear lower panel 22 arelocated just before the rear lower/bottom panel fold line 24. Thefunction of these notches is to prevent an interference condition fromoccurring when the right and left end panels 14 and 18 and the rearlower panel 22 are all folded upwardly. The right and left intersectionnotches 34 and 36 facilitate the formation of a corner joint betweenthese three intersecting planar surfaces.

The shape of the completed overhead stowage bin 10 can be generallydescribed as a rectangular, polygonal open-fronted box-type structure.Referring again to FIG. 1, it can be seen that the stowage bin 10 isgenerally rectangular when observed from a proximal (front) view of theopen-fronted structure (right-hand side in FIG. 1). As can be moreclearly seen in FIG. 3, the stowage bin 10 can also be describedgenerally as an asymmetrical six-sided polygon. The forward or inboardside of the stowage bin defines an opening 37 in the bin's completedfinal stage.

Referring again to FIG. 2, the interlocking joints of the stowage bin 10are a modified-type of mortise and tenon joint described as minimum edgemargin mortise and tenon joints. This joint is formed from theintersection of an orthogonally disposed tenon panel and mortise panel.The tenon panel is illustrated as having “square cut” tenon tabs formedon the marigonal portions of the respective panels. As shown in thedrawings, the tenons have parallel, continuous, planar opposite sidesdevoid of transverse projections, recesses or hooks, and are of constantthickness from their root portions, by which they are cantileveredoutward, to their free end edges. The mortise panel is illustrated ashaving “square cut” mortise pocket cutouts with no dovetailing or otherangling cut utilized in the sides or edges of the tenon tabs or mortisepocket cutouts. On the aircraft stowage bin 10, four right end paneltenon tabs 51, 52, 53, and 54 are located along the right panel upperedge 15. The four left end panel tenon tabs 57, 58, 59, and 60 arelocated on the left end panel upper edge 19.

In the minimum edge margin mortise and tenon joint of the presentinvention, the mortise pockets are located along the edge of the mortisepanel as in a rabbet joint but with the mortise panel edge containingoutwardly extended bulges in the regions of the mortise pockets. Thisdefines a minimum edge margin around each mortise pocket cutout insteadof the mortise pocket sidewalls being incorporated directly into thepanel edge as in a rabbet joint. An inherent advantage of the edgemargin mortise and tenon joint of the present invention is that the loadimposed on the joint extends through the minimum edge margin of thepanel, instead of being forced through the bondline of an adhesive,which are commonly used to secure prior art joints. The panel togetherwith the minimum edge margin can carry a substantially greater load thancan an adhesive bondline.

Referring again to FIG. 2, the stowage bin 10 utilizes eight minimumedge margin mortise pockets, four on the right and four on the left.Specifically, in the present invention there are three minimum edgemargin mortise pockets 63, 64, and 65 on the rear upper panel right edgemargin 27 and one minimum edge margin mortise pocket 66 on the top panelright outer edge 31. Correspondingly, there are three minimum edgemargin mortise pockets 71, 72, and 73 on the rear upper panel left edgemargin 28 and one left top panel minimum edge margin mortise pocket 74on the top panel left outer edge 32.

In the preferred embodiment of the present invention, the right sidewall tenon tabs 51, 52, 53, and 54 and the left side wall tenon tabs 57,58, 59, and 60 are disposed along on the right and left end panel upperedges 15 and 19 respectively, so that a lateral load is carried throughthe edge margins of the mortise pockets 63, 64, 65, 66, 71, 72, 73, and74. Alternative embodiments of this invention may utilize a greater orlesser number of minimum edge margin mortise pockets depending on theloading requirements for the particular applications involved.

Since the tenon tabs are located on the upper edge portions of the endpanels and the mortise pockets are located on the outer edge portions ofthe rear upper panel and the top panel, a limited number of foldingsequences are needed to form the stowage bin 10 One preferred sequenceis to first fold up the right and left end panels 14 and 18 along foldlines 16 and 20, and then fold the top panel 30, the rear upper panel 26and rear lower panel 22 in that respective order. This particularfolding sequence allows the mortise and tenons to engage together as thebox structure is formed.

As can be seen by careful examination of FIG. 2, the right mortisepockets 63, 64, 65, and 66 and right tenon tabs 51, 52, 53, and 54 donot align symmetrically with the left mortise pockets 71, 72, 73, and 74and the left end panel tenon tabs 57, 58, 59, and 60, but rather arestaggered relative to each other. This design allows two identicalstowage bins (or indeed an entire row of stowage bins) to nest in closeproximity to one another with the right extending minimum edge marginbulges 81, 82, 83, and 84 forming a “zipper-like” connection with theleft extending minimum edge margin bulges 89, 90, 91, and 92 of anidentical adjacent bin. Thus, this pattern permits these stowage binswhen installed adjacently to achieve maximum total volume with respectto a specified aircraft interior envelope.

The outer longitudinal sidewalls 163, 164, 165, and 166 are thelongitudinal sidewalls of the right mortise pockets 63, 64, 65, and 66that are the closest to the rear upper panel right edge margin 27 andthe top panel right edge margin 31. In a preferred embodiment, the outerlongitudinal sidewalls 163, 164, 165, and 166 are in linear alignmentwith the rear upper panel right edge margin 27 and the top panel rightedge margin 31, with only the right minimum edge margin bulges 81, 82,83, and 84 extending beyond the right panel edge margins 27 and 31. Thistype of minimum edge margin mortise and tenon joint design allows thevolume of the stowage bin 10 to be maximized.

Correspondingly, the outer longitudinal sidewalls 171, 172, 173, and 174are the longitudinal sidewalls of the left mortise pockets 71, 72, 73,and 74 that are the closest to the rear upper panel left edge margin 28and the top panel left edge margin 32. In a preferred embodiment, theouter longitudinal sidewalls 171, 172, 173, and 174 are in linearalignment with the rear upper panel left edge margin 28 and the toppanel left edge margin 32, with only the left minimum edge margin bulges89, 90, 91, and 92 extending beyond the left panel edge margins 28 and32. Alternative embodiments of this invention might vary the locationand alignment of the mortise pockets along the panel edge margins andwith respect to the pocket's respective minimum edge margin bulges toaccommodate specific applications.

Referring to FIG. 3, ideally the mortise pockets are illustrated as notpenetrating the entire thickness of the rear upper panel 26 or the toppanel 30. In one preferred embodiment, the mortise pocket cutoutspenetrate through one side of the thermoplastic composite skin and thehoneycomb core, but not through the second side of the thermoplasticcomposite skin. The length of the extended tenon tabs from the left andright end panels 14 and 18 should approximate the depth of the mortisepockets for preferred nesting of the interlocking joint. This type ofjoint is referred to as a “blind joint” since the joining method cannotbe seen after the joint is engaged. In an alternate embodiment, themortise pockets may penetrate the entire thickness of the compositepanel.

Rather than defining, a blind joint, the mortise pocket may penetratethrough the entire thickness of the mortise panel In this construction,the load path through the joint extends through both the upper and lowerskins of the mortise panel since both skins are in contact with thetenon. This provides a stronger, larger load carrying capacity joint,especially if no adhesive is used at the joint.

Right and left metallic formed angle brackets 38 and 40 secure the toppanel 30 to the right and left end panels 14 and 18, as shown in FIG. 1.The top and end flanges of the brackets 38 and 40 are through-bolted,respectively, to the top panel 30 of the bin and the end panels 14 and18 such that the brackets provide a load path for downloads imposed onthe bottom panel 12, locking the box together so that the tenon tabscannot be pulled out of the mortise pockets. In this preferredembodiment, only these two brackets 38 and 40 are required to hold theone piece stowage bin together This is a substantial reduction in partcount as well as weight savings providing substantial advantages overalternatives in the prior art.

This folded one piece composite panel stowage bin 10 has the addedadvantage of not requiring a bonding adhesive. The use of adhesivebonding of joints has virtually always been necessary in aerospacejoinery techniques that utilize composite materials. The removal ofbonding adhesive for securing joints eliminates substantial applicationand cure time of the adhesive, generally on the order of eight hours. Itcan also eliminate the need for expensive and complicating tooling.Thus, both time and money can be saved in the production of a stowagebin 10 that does not require adhesive for securing its joints.

Another aspect of the present invention is shown in FIG. 7, whichillustrates the utilization of self-tooling characteristics into themortise and tenon joint. Due to limitations in tolerance control incomposite sandwich panel formation, the right and left square cut tenontabs 51, 52, 53, 54, 57, 58, 59, and 60 are produced substantiallysmaller than their corresponding right and left mortise pocketcounterparts 63, 64, 65, 66, 71, 72, 73, and 74. This methodology helpsto ensure that variation in tenon panel thickness does not prevent theflat tenon tabs from being able to engage in the mortise pockets. Theresidual gapping which results between the mortise pocket sidewalls andthe tenon tab surfaces is unwanted however, because the resulting jointis insecure and requires some type of additional fastening technique. Itis also difficult to achieve acceptable final part tolerancespecification levels with large variations designed into the joiningprocesses.

The present invention incorporates protrusions 120 a into the sidewallsand endwalls of the mortise pockets 63, 64, 65, 66, 71, 72, 73, and 74that extend into the interior of the mortise pockets. These protrusionsare illustrated in FIG. 7 as being of wave-like or generallysemi-circular shape, and are sized to form an interference fit with theflat tenon tabs when they engage into their respective mortise pockets.The interference fit is achieved through a combination of springdeflection of the wave-like protrusions by the tenon tabs and localmaterial removal from the tips of the “waves” as the tenons areinserted.

In the preferred embodiment, as shown in FIG. 7, the wave-likeprotrusions are disposed along both longitudinal sidewalls of themortise pockets to secure the tenon tab in the center of the mortisepocket. In an alternative embodiment, the wave like protrusions could bedisposed only along one longitudinal sidewall so that the oppositelongitudinal sidewall would be forced into substantially fill contactwith the adjacent surface of the extended tenon tab, for use in specificapplications. The wave-like protrusions act as self-tooling component ofthe joint, that is capable of independently securing the tenon panel tothe mortise panel, without the assistance of expensive additionaltooling.

It will be appreciated that the protrusions 120 a may be formed inshapes other than as illustrated and described above. For instance, theprotrusions can be in the shape of peaks, truncated peaks, triangles,truncated triangles, saw teeth, truncated saw teeth, etc. See FIGS. 8and 9, and protrusions 120 b and 120 c respectively in this regardIdeally, but not essentially, the protrusions are tapered in thedirection into the interior of the mortise pockets.

It will also be appreciated that the mortise pocket can be formed inshapes other than the rectangular shape shown in FIGS. 4, 5, and 7. Forinstance, the mortise pocket can be square, oval, round, etc. In thesecircumstances, the tenon is shaped to snugly engage the mortise pocket.

It will further be appreciated that the present invention may beutilized in conjunction with mortise and tenon panels that are disposedat angles other than orthogonally to each other, as shown in FIGS. 4 and5. For example, applicants anticipate that the mortise and tenon jointof the present invention may be utilized with mortise and tenon panelsthat are disposed anywhere from 45° to 135° relative to each other. Inthese situations, the mortise pocket is formed in the desired anglerelative to the surface of the mortise panel Also, the edge of the tenonpanel adjacent the tenon tab is angled accordingly.

The present invention has been described in relation to a preferredembodiment and several alternate embodiments. One of ordinary skillafter reading the foregoing specifications, may be able to effectvarious other changes, alterations, and substitutions or equivalentswithout departing from the broad concepts disclosed. It is thereforeintended that the scope of the letters patent granted hereon be limitedonly by the definitions contained in the appended claims and theequivalents thereof.

The embodiments of the invention in which an exclusive property orprivilege is claimed are defined as follows:
 1. A self aligning mortiseand tenon joint structure, comprising: (a) a mortise panel havingportions defining at least one mortise pocket in the mortise panel, themortise pocket having a perimeter wall; (b) a tenon panel comprising atleast one flat tenon tab protruding from the tenon panel, the tenon tabhaving parallel, continuous, planar opposite sides devoid of transverseprojections, recesses or hooks and of constant thickness, the tenon tabbeing shaped to correspond to the cross-sectional shape of the mortisepocket, said protruding tenon tab being insertable into said mortisepocket; and (c) at least one protrusion extending inwardly from theperimeter wall of the mortise pocket and into the interior of themortise pocket, said protrusion being sized to form an interference fitwith the flat tenon tab received within the mortise pocket through acombination of local material removal and spring deflection of theprotrusion by the tenon tab, said protrusion acting as a self-toolingfeature, capable of independently securing the tenon panel to themortise panel.
 2. A structure according to claim 1, wherein the tenonand mortise panels are composed of a composite honeycomb material inwhich the engagement of the tenon tab in the mortise pocket, results innominal gapping between the mortise pocket perimeter wall and theadjacent surface of the tenon tab, on the order of approximately 0.020inches.
 3. A structure according to claim 1, wherein the tenon panelcontains a plurality of extended tenon tabs, and the mortise panelcontains a plurality of corresponding mortise pockets.
 4. A structureaccording to claim 1, wherein a plurality of said protrusions are spacedapart along the perimeter wall of the mortise pocket, whereby the tenonpanel is positioned and maintained generally centered within the mortisepocket.
 5. A structure according to claim 1, wherein the protrusions arelocated only along a portion of the perimeter wall of the mortisepocket, such that the tenon tab is forced into substantially fullcontact with the portion of the mortise pocket perimeter wall devoid ofprotrusions.
 6. A structure according to claim 1, wherein the mortisepocket extends only partially through the thickness of the mortisepanel.
 7. A structure according to claim 1, wherein the mortise pocketpenetrates entirely through the mortise panel.
 8. The structure of claim1, wherein the mortise panel is positioned non-orthogonally to the tenonpanel.
 9. The structure according to claim 8, wherein the mortise panelis disposed at an angle from 45° to 135° to the tenon panel.
 10. Astructure according to claim 1, wherein the protrusions of the mortisepocket are tapered in the direction into the interior of the pocket. 11.A structure according to claim 10, wherein the shape of the protrusionsare selected from the group consisting of waves, truncated waves, peaks,truncated peaks, saw teeth, truncated saw teeth, semicircles, truncatedsemicircles, triangles, and truncated triangles.
 12. A structureaccording to claim 11, wherein said protrusions are wave shaped andcomprise a generally circular shaped curvature in the direction acrossthe curvature, with a major radius of approximately 0.063 inches and aminor radius of approximately 0.125 inches, the protrusions alsocomprising protrusion tips that extend approximately 0.045 inches intothe interior of the mortise pocket.
 13. A structure according to claim1, wherein the mortise pocket of the self-aligning mortise and tenonjoint is tilled with a bonding adhesive.
 14. A structure according toclaim 13, wherein the protrusion is capable of independently supportingthe tenon panel and mortise panel engaged together while the bondingadhesive is uncured.
 15. A minimum edge-margin mortise and tenon jointcorner structure, comprising: a tenon panel member; a mortise panelmember defining a plane, the mortise panel member being arrangedangularly to the tenon panel member; a row of spaced tenon tabsextending outwardly from the tenon panel member, each of said tabshaving opposite side surfaces that are arranged angularly to the planedefined by the mortise panel member; the mortise panel member having arow of mortise pockets spaced apart for receiving the tenon tabstherein, each of said mortise pockets being generally in the shapecorresponding to the cross-sectional shape of the associated tenon tabreceived therein, said mortise pockets having respective interiorperimeter walls; the mortise panel member having an edge margin with themortise pockets adjacent to said edge margin, the edge margin havingportions defining a series of bulges that extend outward from themortise panel edge margin in the regions of the mortise pockets, suchthat the edge margin maintains a minimum width around each of themortise pockets with the mortise panel pockets received in differentbulges, respectively.
 16. A structure according to claim 15, wherein aportion of each of the mortise pocket interior perimeter walls closestto the mortise panel edge margin is defined as the outer longitudinalsidewall, said outer longitudinal sidewall being aligned withnon-bulging portions of the mortise panel edge margin.
 17. A structureaccording to claim 15, wherein the tenon and mortise panel members areeach composed of a composite honeycomb material in which the engagementof the tenon tabs in the mortise pockets results in nominal gappingbetween the mortise interior perimeter walls and the adjacent surfacesof the tenon tabs, on the order of approximately 0.020 inches.
 18. Astructure according to claim 15, including at least one protrusionextending inwardly into the interior of each of the mortise pockets fromthe interior perimeter wall of such mortise pocket, said protrusionbeing sized to form an interference fit with the associated tenon tabengaged into such mortise pocket through a combination of local materialremoval and spring deflection of the protrusion by the associated tenontab, said protrusion acting as a self-tooling feature, capable ofindependently securing the tenon panel member to the mortise panelmember.
 19. A structure according to claim 18, wherein a plurality ofprotrusions are located along the interior perimeter wall of each of themortise pockets, whereby the tenon panel member is positioned andmaintained generally in the center of the row of mortise pockets.
 20. Astructure according to claim 18, wherein the protrusions are tapered inthe direction into the interior of the pockets.
 21. A structureaccording to claim 20, wherein the shape of the protrusions is selectedfrom the group consisting of waves, truncated waves, peaks, truncatedpeaks, saw teeth, truncated saw teeth, semicircles, truncatedsemicircles, triangles, and truncated triangles.
 22. A structureaccording to claim 15, wherein the mortise pockets contain a bondingadhesive.
 23. A structure according to claim 15, wherein the mortisepockets extend only partially through the thickness of the mortise panelmember.
 24. A structure according to claim 15, wherein the mortisepockets penetrate entirely through the mortise panel member.
 25. Astructure accordingly to claim 15, wherein the bulges are of a length atleast as long as the length of the respective mortise pockets extendingalong the outer longitudinal sidewall of the mortise panel member.